Two;  I found three diaphragms in the short whistle and one in the long one

Three; The whistles have two different name plates, although the whistles look very similar and I was always under the impression that they were both Cunningham Whistles.

The shorter whistle plate says Cunningham Air Whistle, size 3MS,  Pressure 40-140.

This agrees with this link  http://www.olympicinstruments.com/cunningham/cunningham.html   on Cunningham Air Whistles “All Whistles are set for operation over a range of 40 to 140 P.S.I..”  I’m still safe as my compressors max out at 125

The Cunningham web site only lists a 3M , not an 3MS and the spec sheet says the overall length for a 3M  is 16 ½ inches, mine measures 15 ¾ inches.

The spec sheet does not list the number of diaphragms.  The Instruction sheet for installing diaphragm and adjusting whistle does not list a whistle size of 3, but a whistles size 4 takes three

The larger whistle states it is a Federal Signal Corporation. It looks almost identical to the shorter Cunningham. Size is a 6L. I can find no specs for it on the Federal Signal wed site. It measures 18 ½ inches long. It contained only one diaphragm. It also states the operating pressure is 70 – 90 pounds which, I guess, is why it blows so easily, I have been using too much pressure